The taste for the blood of human prey must be pretty overwhelming for a grizzled political werewolf like Menzies Campbell. He can't get enough of it. Certainly Charles Kennedy's 80 proof claret clearly wasn't enough to slake a thirst like Ming's, even though it did poison his leadership. Now he's stalking little Bercow, too, and seeking to replace him, just like he did with Kennedy, as Iain Dale reports.
I'm suggesting there must be some sort of political bloodlust at work here, because he certainly can't be doing it consciously. He who wields the knife seldom wears the crown and all that. At least, not for very long. You would have thought he of all people would have learnt that lesson pretty comprehensively. It seems not. So no, Ming must be driven by some kind of supernatural desire to decapitate colleagues, even those that pose no threat to him - though perhaps do represent an obstacle to his ambition. Target and destroy.
Even so, I would not be sorry to see that duplicitous little git Bercow ousted, even by a fresh-brains-addicted political LibDum zombie like Menzies Campbell. But it's just worth remembering now and then that the ends seldom justify the means. Whatever the outcome, however joyful, the "means" have a habit of coming back and biting you in the ass.